In balloon angioplasty or PTCA, a catheter is advanced through the arterial system of a patient to an area of stenosis where an artery is partially or completely blocked. The catheter, with the balloon deflated, is advanced through the stenotic area, and then the balloon is inflated to expand the stenosis.
With conventional catheters for angioplasty, the blood flow is completely blocked while the balloon is inflated. This tends to limit the amount of time that the inflation of the balloon can be tolerated by the patient.
Thus, in Sahota U.S. Pat. No. 4,581,017; Sogard et al. U.S. Pat. No. 4,944,745 and Horzewski et al. U.S. Pat. No. 4,771,777, among others, balloon catheters for angioplasty are disclosed in which the balloon can be inflated without completely blocking the blood flow through the artery in which the balloon is inflated. However, in the prior art designs, the flow capacity of blood through the inflated balloon may be undesirably low and/or may be undesirably turbulent for the handling of blood. Also, difficulties may be encountered in some of the prior art designs with respect to the advancement of the guidewire, because of the presence of a side aperture through which the guidewire may accidentally project during advancement.
In accordance with this invention, an intravascular balloon catheter is provided which addresses the above problems. A guidewire may be reliably advanced through the catheter of this invention without risk of the guidewire projecting laterally out of a side aperture in the catheter, thus becoming stuck and non-advanceable. Additionally, the catheter of this invention can provided a relatively laminar, non-turbulent, high volume flow of blood through an inflated balloon in an artery when that is required. At the same time, this flow of blood may be shut off when the guidewire or the catheter are being advanced, and then reopened at any desired time for selective and beneficial clinical advantage.